Ease into interval training. “Build up your intensity intervals slowly, especially for someone who’s deconditioned,” says fitness trainer Sue Grant, supervisor of the active older adult fitness program at the Magdalena Ecke Family YMCA in Encinitas. “Try just one or two higher intensity intervals during each workout at first. As your stamina improves, challenge yourself to (increase) the pace.”

Warm up and cool down. “Make sure you just don’t jump into intense interval training,” Grant says. “To warm up, just do a little mini-version of what you’ll be doing in the hard part of your workout.” To cool down, slowly lower the intensity of activity until you’re breathing normally.

Not every day. Don’t perform interval work on consecutive days. You need to let your body recover and avoid burnout. Every other day or three times a week will produce results with less risk of injury.

Make changes slowly over a period of time. As you become stronger with more endurance, gradually increase the intensity or duration of intervals, but not both at the same time.

Set training goals that are attainable and safe for your physical condition. Although regular interval training will produce results, don’t expect overnight miracles.

Make your intensity intervals an all-out effort. The high-intensity phase should be long and strenuous enough that you’re out of breath, typically one to four minutes of exercise at about

80 percent to 85 percent of your maximum heart rate. Recovery periods should not last long enough for your pulse to return to a resting rate.

Keep it up. The intensity that makes intervals work can’t get easier as you get fitter. You must constantly push yourself and mix in different activities. It doesn’t matter what type of cardio you do — riding a recumbent bike, running stairs or walking at the beach — just keep turning up the intensity over time.

Take precautions. Heart or stroke patients, people who have high blood pressure or anyone over 65 can interval train, but they must do it carefully. “These people need to wear a heart rate monitor, and their physician should give them a maximum exercise heart rate and (the exerciser) needs to stay within that prescribed range,” said Richard Cotton, a Carlsbad exercise physiologist and national director of certification for the American College of Sports Medicine.

— R.J. IGNELZI

Kudos to you. In an effort to boost your health and fitness levels, you diligently walk, run, cycle (pick your cardio activity) for hours each week. But what if you could get the same or better results exercising in just half the time?

Interval training, an exercise regimen that alternates bursts of intense activity with intervals of lighter movement, offers an expedient way to improve cardiovascular fitness, burn optimal calories and keep a workout challenging. Once reserved for fine tuning elite athletes, this type of fitness program now is being used by anyone of any age who wants the most effective workout in the least amount of time.